B3 Question Which process occurs in the mitochondria in cells? Why do the liver and muscle cells have large number of mitochondria? What is the function of the ribosomes? Answer Respiration occurs in the mitochondria in cells. Liver and muscle cells require more energy so have more mitochondria. Ribosomes are the site of protein synthesis. Where are the ribosomes situated? Ribosomes are in the cytoplasm What do you need to use to see A microscope. ribosomes and some other structures in cells? What substance are chromosomes made Chromosomes are made of DNA of? What do chromosomes carry? Coded information in the form of genes. What is the name of the coded The genetic code information in genes? What does DNA control? DNA controls the production of proteins What are proteins needed for? Proteins are needed for growth and repair. What is the structure of DNA? DNA has two strands coiled to form a double helix Each strand contains chemicals called bases there are four types Cross-links are formed between the strands by pairs of bases. Chromosomes are divided into areas Genes. called? What does each gene contain? Each gene contains a different sequence of bases Each gene codes for a particular protein. Where are proteins made? Proteins are made in the cytoplasm (ribosomes) Why is a copy of the gene needed to make proteins? A copy is needed because the gene itself cannot leave the nucleus. What are the four letters that A, T, G and C represent the four bases in DNA? What are the complimentary base A-T and G-C. pairs?? What does the base sequence in DNA determine in proteins? The base sequence determines the amino acid sequence in proteins. What is the name of the molecule that mrna takes information from DNA to the ribosomes takes information from the DNA to the ribosomes? How does DNA control cell function? DNA controls cell function by controlling the production of What are the names of the scientists that first worked out the structure of DNA? proteins some of which are enzymes. Watson and Crick were the first to work out the structure of DNA. What information from other scientists did Watson and Crick use to determine the structure of DNA? Why wasn t Watson and Crick s discovery accepted immediately? X-ray data showing the double helix structure Data indicating that the bases occurred in pairs Work of scientists needs to be repeated or tested by other scientists before it is accepted. Give three examples of proteins. Collagen Insulin Haemoglobin. What are proteins made of? Long chains of amino acids
What are the functions of proteins? Structure (collagen) Hormones (insulin) Carrier molecules (haemoglobin) Enzymes Why do proteins have different functions? Different proteins have different functions because they have different sequences of amino acids. What do enzymes do to chemical Enzymes speed up chemical reactions reactions? What are enzymes made of? Enzymes are proteins. When do enzymes work best? Enzymes work best at certain temperatures Which biological processes do enzymes Respiration catalyse? Photosynthesis Protein synthesis. What is meant by the lock and key Enzymes have a high specificity for their substrate mechanism? Enzymes have an active site that only fits certain substrates How can the rate of an enzyme catalysed By changing the ph reaction be changed? By changing the temperature. What happens to enzymes at high temperature or ph? Enzymes denature at extreme temperature or ph Denaturing in an irreversible process and stops the enzyme from working properly Denaturing changes the shape of the active site. What does denaturing do to the enzyme s active site? What are gene mutations? Changes to genes What will different cells produce? Different cells will produce different proteins. What might gene mutations lead to? Gene mutations may lead to the production of different proteins. How can mutations occur? Spontaneously Due to radiation Due to chemicals Are mutations always harmful? Mutations are not always harmful; they can sometimes be beneficial or have no effect. Do all cells use the full set of genes No, some genes are switched off. contained in each cell? Which cells are switched off determines the function of the cell How do genetic mutations lead to different protein production? Gene mutations change the sequence of bases in the gene which leads to changes in the amino acid sequence in the protein produced. Where does the energy for all life processes come from? What is the word equation for respiration? Which processes require energy from respiration? What is the symbol equation for photosynthesis? Respiration Glucose + oxygen carbon dioxide + water Muscle contraction Protein synthesis Control of body temperature in mammals C 6H 12O 6 + O 2 CO 2 +H 2O. Apart from carbon dioxide and water what substance does respiration result in the production of? ATP What is ATP used for? ATP is the energy source for many processes in cells Why can oxygen consumption be Because aerobic respiration requires oxygen used as an estimate for metabolic
rate? Why is the rate of respiration influenced by changes in ph and temperature? Why do breathing and pulse rate increase during exercise? Why does anaerobic respiration take place during hard exercise in addition to aerobic respiration? What is the name of the substance produced by anaerobic respiration that causes pain and fatigue? What is the word equation for anaerobic respiration? Which process produces the most energy per glucose molecule aerobic or anaerobic respiration? What is fatigue in terms of lactic acid build up (oxygen debt) and how is this removed during recovery? Enzymes are used in respiration and changes in ph and temperature will cause the enzymes to denature. The muscle cells require more oxygen when exercising. Oxygen cannot be supplied to the muscles fast enough for all energy required to be produced by aerobic respiration. Lactic acid Glucose lactic acid Aerobic respiration Hard exercise causes lack of oxygen in cells This results in the incomplete breakdown of glucose. Continued panting after exercise to replace oxygen allowing aerobic respiration Heart rate increased to ensure that blood carries lactic acid away to the liver. In terms of cells, what is the difference between an amoeba and a dog? An amoeba is a unicellular organism and a dog is a multicellular organism. What are the advantages of being Allows organisms to be larger multicellular? Allows for cell differentiation Allows organism to become more complex. Why do multicellular organisms Communication between cells require specialised organ systems? Supplying the cells with nutrients Controlling exchanges with the environment. How are chromosomes arranged in most They are arranged in pairs. body cells? Why do chromosomes have to be copied to produce new cells? So that the new cells have exactly the same genetic information as the original. Why is cell division necessary? To replace worn out cells To repair damaged tissue For asexual reproduction What is the name of the process that Mitosis creates new cells for growth? What are cells that have two copies of Diploid each chromosome called? Why does DNA have to be replicated before cells divide? So when the cell divides the daughter cells have a complete set of DNA. How does DNA replicate? The DNA unzips to form single strands. New double strands forming by complementary base pairing. What happens to chromosomes The chromosomes line up along the centre of the cell. during mitosis? They then divide The copies move to opposite poles of the cell. What are sperm and egg cells called? Gametes What happens to gametes during The gametes join during fertilisation. fertilisation? How many chromosomes do gametes have in comparison to body cells? Gametes have half the number of chromosomes compared to body cells. When creating a unique individual where do half the genes come from? In sexual reproduction to produce a unique individual half the genes come from each parent.
Why are sperm cells are produced in large numbers? How are gametes produced? What is the term for a cell with one copy of each chromosome? Why does fertilisation result in genetic variation? Why does a sperm cell have many mitochondria? What does the acrosome in a sperm cell do? Why is the chromosome number halved in meiosis? To increase the chance of fertilisation. Gametes are produced by meiosis. Haploid Gametes combine to form a diploid zygote Genes on the chromosomes combine to control the characteristics of the zygote. To provide energy The acrosome releases enzymes to digest the egg membrane. One chromosome from each pair separate to opposite poles of cells in the first division In the second division the chromosomes divide and move to the opposite ends of the cell This makes each cell genetically different. What is the function of the red blood Red blood cells carry oxygen around the body cells? What is the function of the white blood White blood cells protect the body from infection cells? What is the function of platelets? Platelets help blood to clot How is a red blood cell adapted to its Small enough to fit through the membranes of capillaries function? Shaped so that it has a large surface area Contains haemoglobin to carry oxygen and carbon dioxide No nucleus to maximise space to carry oxygen and carbon dioxide What is the function of plasma? Carries other chemicals around the body What is the name of the substance Oxyhaemoglobin formed when oxygen and haemoglobin react? Where does the reverse of the above In the tissues reaction take place? What are the three blood vessels in the Arteries body? Veins Capillaries What do the three blood vessels in the Arteries transport blood away from the heart body do? Veins transport blood to the heart Capillaries exchanging materials with tissues How are the three blood vessels Arteries have thick muscular and elastic walls adapted to their functions? Veins have large lumen and values to prevent back flow Capillaries have permeable walls Where does the right side of the heart The right side of the heart pumps blood to the lungs pump blood to? Where does the left side of the heart pump blood to? The left side of the heart pumps blood to the rest of the body Where is blood at higher pressure Blood is at higher pressure in the arteries veins or arteries? Why does blood flow from one place to another? Blood flows from areas of high pressure to areas of low pressure What do the left and right ventricles in They pump blood. the heart do? Why does the left ventricle have a thicker muscle wall than the right ventricle? The left ventricle has to pump blood around the entire body.
What do the left and right atria in the heart do? What do the semilunar, tricuspid and bicuspid valves do in the heart? What are the four main blood vessels of the heart? What is the advantage of the double circulatory system in mammals? The receive blood. They prevent backflow. Aorta Vena cava Pulmonary vein Pulmonary artery Can pump at higher pressure Therefore greater rate of flow to the tissues What is the function of the vacuole in a Contains cell sap and provides support plant cell? What is the cell wall made of? Cellulose to provide support What is the difference between bacterial and animal and plants cells? Bacterial cells are simpler and smaller than animal and plant cells. What do bacterial cells lack? A true nucleus Mitochondria Chloroplasts How is the arrangement of the DNA in No nucleus in a bacterial cell a bacterial cell and an animal/plant cell different? Circular strand in a bacterial cell and chromosomes in an animal/plant cell How can growth be measured? As an increase in height As an increase in wet or dry mass What is the best measurement of Dry mass growth? When are the two rapid phases of One just after birth growth in human growth? One in adolescence How can growth be described in terms of Cell division then cells becoming specialised cell division? What is the process by which cells Cell differentiation become specialised called? What are undifferentiated cells called? Stem cells Where are stem cells obtained from? Embryonic tissue What can stem cells develop into? Different cells, tissues and organs What is the difference between adult and embryonic stem cells? Adult stem cells can only become certain cells. Embryonic stem cells can become all types of body How is animal and plant growth different? What is the name of the areas of plants where cell division happens? What is the main method by which plants gain height? What do many plant cells keep but most animals lose at an early stage? cell Animals only grow in the early stages of their lives and reach a finite size Plants grow continually All parts of an animal are involved in growth Plants grow at specific parts of the plant. Meristems Cell enlargement The ability to differentiate What is the process of selective Selection of desired characteristics breeding? Cross breeding individuals with those characteristics Selection of suitable offspring over may generations What can selective breeding lead to? Inbreeding which can cause health problems within the species How can selective breeding reduce Accumulation of harmful recessive characteristics
the gene pool? Reduction in variation What is artificially transferring genes Genetic engineering or genetic modification from living to another called? Give an advantage of genetic engineering Give a risk involved with genetic engineering Give three examples of genetic engineering What is the process of genetic engineering? What might it be possible for genetic engineering to do in the future? What is it called when a person s genes are changed in an attempt to cure disorders? What type of cells could gene therapy involve? Why is gene therapy involving gametes controversial? Organisms with desired features are produced rapidly Inserted genes may have unexpected harmful effects Inserting the gene from carrots that produces betacarotene into rice so that humans can process betacarotene into vitamin A from rice. Production of human insulin by genetically engineered bacteria Transferring resistance to herbicides, frost damage or disease to crop plants Selection of desired characteristics Isolation of genes responsible Insertion of genes into other organisms Replication of these organisms Change a person s genes and cure certain disorders Gene therapy Body cells or gametes If genes can be changed to cure disorders before conception, what other genetic characteristics could be changed prior to conception of a baby?